1: Double useless, something with no point at all. Comes off of "tits on" any male mammal, since males don't nurse the young; chickens of course don't nurse their young at all, so tits would be especially useless on a rooster.

2: derogatory for tiny or very small breasts

He's not even tits on a boar, at best he's tits on a rooster.

So we had it about worked out when Tits on a Rooster finally showed up, and it all had to have his input.